Ever more stringent restrictions on pollutant emissions of motor vehicles make it necessary to keep pollutant emissions as low as possible. One method to do so is by reducing the pollutant emissions that arise during the combustion of the air/fuel mixture in the respective cylinders of the internal combustion engine. A second method may include exhaust-gas aftertreatment systems which convert the pollutant emissions generated during the combustion process of the air/fuel mixture in the respective cylinders into non-hazardous substances. In one example, exhaust-gas catalytic converters convert carbon monoxide, hydrocarbons, and nitrogen oxides into non-hazardous substances. Both reduction of the pollutant emissions during the combustion in the respective cylinder and the conversion of the pollutant components with high efficiency by way of the exhaust-gas catalytic converter necessitate a very precisely set air/fuel ratio in the respective cylinder.
An intake pipe model is described for example in the specialist book “Handbuch Verbrennungsmotor, Grundlagen, Komponenten, Systeme, Perspektiven” [“Internal combustion engine compendium, principles, components, systems, perspectives”], publisher Richard van Basshuysen/Fred Schäfer, 2nd improved edition, June 2002, Friedrich Vieweg & Sohn Verlagsgesellschaft mbH, Braunschweig/Wiesbaden, pages 557 to 559. Furthermore, intake pipe models of said type are also described in EP 0820559 B1 and EP 0886725 B1.